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Heat stress abatement is a challenge for producers in the United States, especially in the southern states. Dairy producers could benefit by having a simply metric to measure heat stress abatement strategies with the goal of motivating improvement in heat stress management. Managing heat stress is key to ameliorating the effects on dairy cow performance. A study was performed to explore the use of a heat stress metric called the Summer to Winter performance ratio (S:W ratio), to quantify and compare farm performance variables among regions of the United States. Summer to Winter ratios were closest to 1.0 in the northern regions and furthest from 1.0 in the southern regions for all performance variables other than milk fat and protein percentage. This suggests that summer performance varies by region and shown using the S:W ratio. A second study compared S:W ratios among Southeast states and then applied the performance ratio to heat abatement strategies in Southeast states. The S:W ratio varied by performance measure and heat abatement strategies but tended to be best for herds implementing cow cooling strategies. The studies in this thesis demonstrated S:W ratios can identify heat stress differences by region and heat abatement strategies by herds.

The transition period for dairy cows is defined as the three weeks pre and postpartum. During the transition period, dairy cows experience a myriad of metabolic, managerial, and nutritional requirement changes. These changes lead to stress and increased susceptibility to diseases which can negatively affect lactational performance in the short and long term. However, dietary amino acid availability can have a dramatic impact on the health and performance of dairy cows around parturition. Thus, the objective of the thesis was to evaluate the effects of supplementing yeast-derived microbial protein, as an alternative protein source for dairy cows during the transition period. This was accomplished by using visual observations and precision dairy monitoring technologies to record disease, feeding behavior, and performance of dairy cows from 21 days prepartum to 150 days postpartum. Yeast-derived microbial protein was found to decrease dry matter intake but not negatively affect milk production or health of the animals. Yeast-derived microbial protein may be used as an alternative protein source for transition dairy cows as it did not negatively affect milk production or health of the animals.

Retention of young cattle and marketing older cattle from the range has been suggested as one of the profitable means of adjustment for the cow-calf operator. This study was to determine the impacts of the shift from cow-calf ranching operation to cow-calf-yearling operation on the feed energy budget of the ranch, cow herd size, beef production and market price of beef. Ten alternative livestock management options involving cow-calf-yearling operations were tested for these impacts, using two representative Utah size ranches (150 and 300 cow ranches). The extra feed needed to accomodate the increased number of yearlings and the decrease required in brood cow herd size were estimated. Changes in beef production in Utah, the Western eleven States, and the change on national price of beef were estimated from marketing projections of four types of beef. These projections were based on three levels of adoption for the management options by producers in each area. Under complete retention of home grown calves, the total amount of feed required to support the typical cow-calf operation was 93% of the total feed needed for the cow~calf short yearling and 85% of the total feed required for the cow-calf long-yearling operation. Only the production of long-yearlings resulted in a considerable decrease in brood cow carrying capacity (8 to 31%)· Marketing baby-beef and grass-fed beef produced a substantial decrease in beef tonnage and a corresponding increase in beef price. Light-fed short-yearlings and heavy-fed beef (from both short and long yearlings) showed a considerable beef increase in Utah and the western region. Only the marketing of heavy-fed short-yearlings produced a positive change in the beef produced nationally and a slight decrease in beef price (0.3 to 2 %) •

Production records for dairy cows were first based on the yield of butter for a seven day period any time during the lactation. Later, 365- day records based on production for one day in each calendar month came into general use. The records preferred at present are 305- day records based on monthly test day production, but calculated using the centering date method. The centering date estimate is based on milk and butterfat production from two consecutive milkings per month. The sampling day is centered as nearly as possible in the test month period which need not coincide with the calendar month. The reason for the general acceptance of the 305- day records is the desire of the dairyman to freshen the dairy cow annually, which means milking for ten months and dry for two months. Records calculated by the centering date method more nearly represent actual production than records calculated by other methods that have been used. It is generally accepted that if the present testing program is used properly it can be of great value to the dairy farmer from the standpoint of herd improvement and for selecting animals for a breeding program. However, only a small percentage of the dairymen take advantage of a testing program. One of the limiting factors has been the cost of testing and record keeping. It has been suggested that bimonthly or trimonthly test periods might provide as much information as the monthly testing interval and at the same time reduce the cost to the individual dairymen. It is reasonable to speculate that with reduced costs there would be an increased number of herds tested. This would help compensate the testing supervisor and data processing center for lost income resulting from less frequent testing, and at the same time provide more information for national sire proving programs. However, bimonthly or trimonthly testing have not been accepted because of the possiblilty of larger error being involved in individual records. This larger error occurs because the curvelinear shape of the lactation is not taken into account and a cow is given credit for the same production over the entire testing period, resulting in either under or over estimation of the record. Tho objective of this study is to measure the relative accuracy of estimating 305- day production of dairy cows by using different testing intervals and different methods to estimate production. Monthly, bimonthly, and trimonthly intervals are studied. Methods include the centering date method and three methods using factors designed to extend production from each test day to a 305-day estimate with the test day estimate averaged to determine the final estimate of production for 305 days.

Importance of problem: Ice Milk is not a new product in the ice cream industry. Rather it is one that has gained only little popularity, except in the preparation of "malts" and "milk shakes"; however, within the last decade the gallonage of ice milk produced has more than doubled. Ice milk has been relatively unimportant because of the difficulty of obtaining a product with acceptable quality. In recent years progressive ice milk manufacturers and research workers have discovered new ingredients and processing procedure that seem to produce favorable results. This low-fat product has several merits that justify its recent popularity, such as low cost to the consumer, high nutritional value, an additional outlet for serum solids, and it is an attractive product to those individuals who may be diet conscious. Ice milk differs from regular ice cream in that it contains less butterfat and more solids-not-fat. Frequently when the fat content is decreased there is a tendency for the product to become coarse. In order to correct this coarseness more milk-solids-not-fat are added to the mix which often effects the flavor of the ice milk. Also with an excessive increase of serum solids in the mix there is danger of sandiness developing in the product during storage. Purpose of problem: The purpose of this experiment is to determine a formula and processing procedure that will yield a frozen ice milk product with desirable flavor, good body and texture qualities, and freedom from sandiness after reasonable storage. By the proper balance and use of ingredients and modern processing and freezing methods it is hoped that the quality goal will be reached and prove beneficial to the industry.

This paper entails the economic and biological responses of both rangeland grasses and livestock grazing rangeland grasses to nitrogen fertilization. Five sites received graduated rates of fertilizer in previous studies. Analysis showed all sites failed to exhibit a significant carry-over response to fertilization. Determination of optimum rate or optimum reapplication schedule was not possible due to residual nitrogen present in the soil. Spring application of fertilizer produced the greatest returns from one site while the other site studied failed to produce a profitable response from either spring or fall application. Calf weight gains were shown to be curvilinear and resulted in the production function: Y = 13.99 + .2049N - .00087N2 where Y is the total pounds of calf gain per acre and N is the pounds of nitrogen applied per acre. Economic analysis of costs and returns of both cow-calf operations and estimates of costs and returns from yearling stockers operations indicated that neither operation was economically feasible.

To provide accurate data concerning sheep losses resulting from predation, a verification study of sheep predation was initiated in March 1972 in the Cedar City area of Utah. In cooperation with the Cedar City Wool Growers Association and Southern Utah State College Experimental Farm, ten sheep ranches were chosen as sample operations, forming the data base for the initial phase of the study (1972-1974). Cooperating ranchers were asked to promptly report all sheep carcasses or injured sheep, so that an examination could immediately be made to ascertain the cause of death or injury. Daily horseback searches were also conducted on the spring and summer ranges. Every located sheep carcass was examined to determine cause of death. If a predator was responsible, the kill was photographed and location, date, species of predator and age class of carcass was recorded. Coyotes were the principal predator inflicting 89 to 100 percent of the kills. Lambs were the principal age class of predator kills. The number of sheep carcasses found and verified as predator kills and natural losses was substantially less than the total number lost. Therefore, a proportion was used to estimate the total predation rate. The average predation rate was 5.9 percent expressed as a percent of lamb crop. In the final year of the study (1975) three herds were chosen and research efforts were intensified and the validity of the statistical inference was confirmed. An estimated total predation loss of 3028 lambs was incurred by herds 1-10 in 1972 to 1974. In 1975, 158 lambs were destroyed by predators in herds 1, 3 and 5. These losses were valued at $89,347. Assuming the sample predation rate is representative of predation losses throughout Utah, the state-wide lamb loss to predators was calculated to be 127,521 lambs, representing a direct income loss to the Utah sheep industry of $3,622,061. The indirect or multiplier losses represented an additional $10,072,911 loss to the state economy. Two models were developed. The first, a cost model, illustrated the nature of the costs of coyote predation, their effects upon the rancher and several approaches to profit maximization with and without coyote predation. The second model approached predation economics from a biological standpoint to identify research needs for future inquiries into predation economics. The relationships between coyote population dynamics, coyote control and predatory sheep losses were discussed, leading to the formulation of an economic production function model. The model provides a conceptual framework to determine the effectiveness and optimum rate of predator control efforts.

A cell synchronization technique was used that consistently yielded numerous elongated chromosomes, which are necessary for producing high-resolution G-banding. The prometaphase stage of contraction was determined to have the greatest utility for detailed comparative analysis and, therefore, was used in the preparation of the proposed standard high-re solution karyotypes and idiogram. A proposed standard high-resolution G-band karyotype of the domestic sheep and goat is presented, along with a high-resolution G-band idiogram of the goat. The karyotypes presented contain considerably more bands than contemporary karyotypes and provide much greater resolution for linear differentiation. The X chromosome of the sheep is acrocentric, rather than having a minute p arm as recently reported. A side -by-side comparison of high-resolution G-band sheep and goat chromosomes indicates identical equivalence of banding patterns. Of special note is the homology of banding patterns for the six acrocentric autosomes of the goat and the respective three submetacentric autosomes of the sheep, reinforcing the evidence that the goat is representative of the ancestral karyotype. C-bands and NORs of the sheep and goat are also presented. When C-banded, the centromeric regions of the sheep and goat acrocentric autosomes were found to be densely stained. The centromeric regions of the X and Y, however, were not stained differently from the chromosome arms. In the sheep submetacentrics, chromosomes 1 and 3 showed weak C-bands while chromosome 2 showed stronger bands. In the sheep and goat, 10 NORs located terminally on five chromosomes pairs were found. Sheep NORs occurred on the three pairs of submetacentric autosomes and on one large and one small pair of acrocentric autosomes. Goat NORs occurred on four large and one small pair of acrocentric autosomes. Sine the banding patterns obtained when staining for NORs do not permit individual identification of each chromosome, duplicate G-banding and silver staining of elongated chromosomes of both sheep and goat would need to be conducted to identify specific NOR-bearing chromosomes.